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Lunar connection on Hanalei Bay stranding nixed.

On the morning of July 3 2004 there was an agitated aggregation of Melon Headed whales in Hanalei Bay, Hawai’i. This event was concurrent to the RIMPAC international naval exercise which happens every two years.

As is typical with these tragic events, the US Navy rolled up their collective sleeves and focused on how to establish that they were not responsible.

In this case they started out with the claim that the exercises were not in progress until after the event. They also sponsored an extensive modeling of the event and presented the findings at the Fall 2004 Acoustics Society meeting. (“Analysis of melon-headed whale aggregation in Hanalei Bay,” David Fromm et. al JASA 2004)

While Dr. Fromm’s presentation was interesting, it was also fraught with data gaps – such as an analysis of the frequencies and signal types used in the exercises. The study also reiterated their claim that the “embayment” happened before the Navy commenced the exercise (which was later in the day than the stranding.).

A critical element that was omitted from the study was that the warships were calibrating their sonar prior to commencing the exercises. These calibrations were coincident to the embayment of the whales.

There were a number of other troubling assumptions that did not square with the incident – including a “lunar” connection (based on an aggregation of melon headed whales that occurred on the same day in Japan). All tolled, it was a well funded, beautifully presented model based on exculpating assumptions – and ultimately signifying very little. The paper has not been published after peer review, and remains in abstract form in the J. Acoustical Society of America.

Noise impacts from military communication sonars are much more widespread than the US Navy would like to admit. ONR is funding research on the impacts, but their priorities seem more focused on how to prevent these embarrassing stranding events from occurring – such as spatial-temporal planning and “recoverable threshold” testing on marine mammals – rather than determining what the mechanism is for the aggravation.

We believe that the Navy could accomplish their mission safely if they chose to examine the signal characteristics that are agonistic and then crafted communication signals that are more benign.

Toward this end we are working on a metrics system that can qualify noise by loudness as well as “roughness” – the characteristic that distinguishes the differences between alarming sounds and pleasant sounds that may be equally loud. Hopefully this ‘metric’ will provide design guidance in the tempering of mid-frequency communication sonar signals.